ES2920606T3 - Acoustic insulation element - Google Patents

Abstract

The invention refers to a sound insulation element (10), which uses a strong force network as a main energy dissipation mechanism, while the strong force network is generated through complex interactions of solid particles (14). in a granular system, which leads to Formation of the maximum number of force interconnecting pairs according to 3rd Newton's law, while the strong force network is realized by using a granular material (12) made of at least one material solid with a specific ascending multimodal particle distribution, comprising a granular material (12) consisting of particles (14), and a support structure (40) having at least one cavity (42), while the cavity at least A cavity (42) is filled with particles (14) of the granular material (12). A distribution is selected that assigns a number (n) of particles (14) to an equivalent external diameter (d) of the particles (14) in such a way that the particles (14) form an energy that dissipates a strong network of force within of the cavity at least one cavity (42), in which the distribution assigning a number (n) of particles (14) to an equivalent external diameter (d) of the particles (14) is an asymmetric distribution, in which the distribution of equivalent external diameters (d) of the particles (14) is multimodal, has several modes, and where said multimodal distribution is skewed, such that said multimodal distribution has a maximum mode (i) that has a maximum number ( n) of particles (14) assigned to a fundamental equivalent external diameter (D,) of particles (14), and wherein said multimodal distribution has at least one anterior mode (I-1) and at least one posterior mode (i+ 1). (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Acoustic insulation element

The invention relates to an acoustic insulation element that uses a strong force network as the main energy dissipation mechanism, where the strong force network is generated through complex interactions of solid particles in a granular system, which leads to the formation of a maximum number of interconnecting force pairs according to Newton's 3rd Law, wherein said strong force network is obtained using a granular material made from at least one solid material with a specific biased multimodal granulometry . The acoustic insulation element comprises a granular material consisting of particles and a support structure having at least one cavity, wherein the at least one cavity is filled with particles of the granular material.

State of the art

Sound insulation elements serve for sound absorption and protection in a wide range of applications. Sound insulation elements are used, for example, on stationary sites such as residential houses, offices or recording studios. On the one hand, the sound insulation elements prevent sound and noise from entering the places that are isolated therewith, and on the other hand, the sound insulation elements prevent sound and noise from leaving said isolated places. . Sound insulation elements are also used in mobile applications, in particular in vehicles, for example passenger cars, mobile homes, caravans, motorhomes, railways, boats, yachts, ships, aircraft and other transportation solutions.

Sound is a pressure oscillation transmitted through a gas, liquid or solid in the form of a traveling wave generated by localized pressure variation in a medium. Sound can be absorbed, transmitted or reflected, Figure 1a. When a sound wave reaches a limit, some of the sound energy is reflected, some is absorbed into the material, and some is transmitted through the material. The proportion that is reflected, absorbed or transmitted depends on the properties of the material and the shape of the boundary reached by the sound wave and the frequency of the sound. If, for example, the boundary is absolutely rigid, that is, the modulus of the material and the stiffness of the boundary are infinite, all sound is reflected, Figure 1b.

The modulus of real materials is always finite. Therefore, some of the sound energy always enters the material in the form of waves. If the boundary stiffness is high, obtained with the thickness of the boundary, waves are the only mechanism of sound transmission through the boundary. However, when the boundary stiffness is small, a substantial part of the sound energy is transmitted by means of macroscopic boundary vibrations, Figure 1c.

When the insulation is fixed to an elastic limit, guaranteeing direct contact between the limit and the insulation, pressure waves are directly transmitted from the limit to the insulation through the contact between two solid bodies. In addition, the vibratory limit also imposes macroscopic vibrations on the insulation. In this case, the insulation essentially acts more like vibration insulation than acoustic insulation, Figure 1d.

EP 2 700 838 A1 discloses a railway sleeper with a damping element to absorb the mechanical excitations generated by a locomotive wheel on a rail, thus a solid-solid interaction. Said railway sleeper also serves for noise reduction within such a railway structure. Thus, noise reduction is achieved by reducing the vibrations of rails, wheels and other structural elements that, as a consequence, generate the so-called noise of structural origin. Therefore, document EP 2700838 A1 describes damping elements for the reduction of mechanical vibrations of solid bodies that are a source of propagated noise of structural origin.

EP 2700839 A1 discloses a damping element for absorbing mechanical vibrations of solid bodies at a given frequency. The vibration isolation damping element comprises a container which is filled with a viscoelastic material, which may be a bulk or granular viscoelastic material. The damping element is then pressurized to increase the stiffness of the element and shift the maximum of its inherent material damping toward the driving frequency of an external load. Said damping element serves, in particular, to damp mechanical vibrations of solid bodies at different frequencies.

GB 2 064 988 A discloses an acoustic damping mesh comprising a flexible layer of material having open pores or cells which are filled at least in part with particles of a higher specific gravity, respectively density, than the material from which it is made. layer is made. The particles are bonded to each other and to the walls between the pores or cells by adhesive. By choosing different materials for the flexible layers, added particles and adhesive, it is possible to control the stiffness of said acoustic insulation. By increasing the stiffness, the amount of noise that is transmitted through the insulation as macroscopic vibrations of the layered composite material can be controlled. The added particles of higher specific gravity, density respectively, will also increase the dissipation of waves traveling through the acoustic damping mesh through reflection, refraction and interference of sound waves. This insulation is a usual state of the art of a multilayer acoustic insulation currently on the market. The document also explains the technological procedure for producing said composite acoustic insulation.

WO 2008/021455 A2 discloses sound attenuation by placing a relatively thin layer of nanocomposite material on a wall, such as a computer case. The acoustic insulation nanocomposite material is obtained by dispersing nanoparticles in a polymeric matrix. Thus, nanofillers increase the elastic modulus of a polymeric matrix and, therefore, contribute to the reduction of the macroscopic vibration of the insulating wall. Simultaneously, the addition of nanofillers to a polymer will reduce wave propagation within the insulating nanocomposite layer, as the nanofillers will act as obstacles to the travel of sound pressure waves, causing reflection and refraction of sound waves.

Document US 2003/0098389 A1 discloses the use of different granular materials having an overall sound speed of less than 90 m/s to dampen vibrations and noise of structural origin generated in aircraft and, in particular, in helicopter structures. . The inventive idea is to reduce the vibration level by filling the empty cavities of the structural elements with such granular materials to achieve frictional vibration reduction. The document shows the model that describes friction as an energy absorption mechanism. Friction occurs between the granular particles and, in particular, through friction between the granular particles and the walls of the structure. To increase the exchange area by friction between the interior faces of the walls, added interior partitions are introduced.

US 2006/0037815 A1 uses a plurality of particles with a density of at least 1 g/cm3 and includes a material that is viscoelastic, elastomeric and/or polymeric to reduce noise and vibrations. By adding different additives made from various other materials to viscoelastic granular materials, and by modifying the size, shape and density of the particulate insulation material, various performance applications can be achieved, such as reduction of vibrational energy, acoustic energy , thermal energy, electromagnetic energy, and/or radio waves. These granular materials can be spread over a flat surface or filled into wall cavities as dry, free-flowing particles. Such particles contact each other and form an insulation with a plurality of dead air cells substantially distributed among the particles. These dead air cells, along with the specific density and viscoelastic properties of the polymer, provide cushioning such as thermal and acoustic insulation. The particulate insulation can be provided in the form of a coating or a paste that can be adhered to the surface. The cushioning is achieved by using a plurality of free-floating particles with a density of at least about 1 g/cm 3 and the material including at least one of a viscoelastic, elastomeric, or polymeric material. The paper highlights the importance of using viscoelastic materials to take advantage of the internal damping of such materials and the energy absorbing effect of free-floating particles.

US 2005/0194210 A1 discloses "Unobstructive Particle Damping Technique" for reducing noise in an aircraft cabin, where particles of various materials collide with each other and with the structure in which the particles are located. In this process, they exchange momentum and convert energy into heat through friction between the particles, and the particles and the interior surface of the structure. Therefore, energy dissipation occurs due to frictional losses, that is, when the particles rub against each other or against the structure, and due to inelastic particle-to-particle collision.

US 5,304,415 A discloses the use of porous members of foamed urethanes, glass wool and the like filled with powder particles having sound absorbing characteristics in a "vibratory state". Sound pressure waves are reduced due to the viscosity friction produced by the walls of the foams or pores as the sound wave propagates through the foams or pores and due to impingement with the vibrating particles.

Document US 2005/0109557 A1 discloses soundproofing panels made up of layers formed by hollow spherical pearls with microperforated porous walls that allow a large amount of sound energy to be dissipated by the viscothermal effect of the air. Therefore, the sound energy is dissipated in this way mainly by the viscothermal effect of the air passing through the dissipation layers and, to a lesser extent, through the porous wall.

EP 1 557 819 A1 discloses sound absorbing structures and processes for producing them. The structures consist of a hollow sphere partially filled with particles, while these particles are free to move within the hollow structures. The hollow structures can then be assembled to form sound insulation structures.

US 5,744,763 A discloses sound deadening material applied to a vehicle hood panel on the side facing the engine compartment. The sound-absorbing material is in the form of a sheet and includes a layer of crumb rubber containing rubber grains of various types of material, various sizes and various shapes, and coating layers covering the layer of crumb rubber. In the present disclosure, noise is absorbed by the rubber grains themselves contained in the crumb rubber layer and by the air gaps present between the grains. The document claims that the sound energy is absorbed by the viscosity resistance and heat transfer of the air present between the rubber grains, and by the friction between the rubber grains that are in contact with each other, thus converting the noise energy into vibrational energy and thermal energy. To the Mixing various kinds of rubber grains with different sound absorption capacity, the insulation can efficiently absorb a plurality of sound frequencies.

CN 204010668 U discloses the use of particles to form a perforated plate structure, while acoustic pores can be considered as a plurality of air resonance sound absorbing structures (Helmholtz resonator). The air in the cavity resonates and goes from friction to heat loss, thus causing sound absorption. US 2005/194210 A1 discloses partially filled honeycomb structures for damping structural vibration and noise energy through flexing (ie bending) of viscoelastic materials, which dissipates mechanical energy (vibration) by converting it in heat. The document claims the so-called non-obstructive particle damping mechanism (NOPD), the particles of various materials collide with each other and with the structure in which the particles are located, exchanging momentum and converting vibrational energy into heat through the friction between the particles. Therefore, energy dissipation occurs due to both frictional losses and inelastic particle-to-particle collisions. NOPD focuses on energy dissipation through a combination of collision, friction and shear damping.

Summarizing the physical principles used to dampen sound and vibrations according to the state of the art, it can be concluded that none of the existing solutions use networks of strong forces as the main energy dissipation mechanism, turning out to be independent of the material and superior to any other currently known dissipative mechanism. It should be noted that any cavity filled with particles could form some force chains along the contacting particles and thus form a "weak network of forces". However, only when the number of force chains is maximized by applying a specific granulometry will a "strong force network" be formed.

Description of the invention

An object of the invention is to provide a granular acoustic insulation element that uses strong force networks as a dissipative mechanism and that provides greater acoustic absorption and noise reduction compared to granular acoustic insulation elements known from the prior art.

A network of forces is generated through complex interactions of solid particles in a granular system, which leads to the formation of a series of interconnecting pairs of forces according to Newton's 3rd Law forming a chain of forces. A large number of force chains form a force network that disperses the direction of force transmission of an incoming sound pressure wave.

Force chains and force networks are known to those skilled in the art. For example, N. S. Nguyen and B. Brogliato, "Multiple Impacts in Dissipative Granular Chains," Lecture Notes in Applied and Computational Mechanics, vol. 72, Springer (2014); K.E. Daniels, "The role of force networks in granular materials," EPJ Web of Conferences 140, Powders & Grains (2017); QICHENG SUN et al, "Understanding Force Chains in Dense Granular Materilas", Int. Mod. J. Phys. B 24, 5743 (2010); P. Richard, M. Nicodemi, R. Delannay, P. Ribiere, and D. Bideau, "Slow relaxation and compaction of granular systems," Nature Materials, vol 4, February 2005; E. Somfai, J.-N. Roux, J. H. Snoeijer, M. van Hecke, and W. van Saarloos, "Elastic wave propagation in confined granular system," Physical Review E 72, 021301 (2005); L. Zhang, N. G. H. Nguyen, S. Lambert, F. Nicot, F. Prunier & I. Djeran-Maigre, "The role of force chains in granular materials: from statics to dynamics", European Journal of Environmental and Civil Engineering, DO1 :10.1080/19648189.2016.1194332 (2016); describe the characteristics of networks of forces.

Additionally, literature such as M. Kramar, A. Goullet, L. Kondie, and K. Mischaikow, "Quantifying force networks in particulate systems," Physica D, 283, 32-55, (2014); R. Arevalo, I. Zuriguel, and D. Maza, "Topology of the force network in the jamming transition of an isotopically compressed granular packing", Physical Review E, 81, 041302, (2010); F. Radjai, DE Wolf, M. Jean, J.-J. Moreau, "Bimodal Character of Stress Transmission in Granular Packings," Physical Review Letters, vol. 80, No. 1, (1998); distinguishes between "weak" and "strong" force networks, according to their topology and size, that is, the number of load-bearing force pairs formed. At present, the formation mechanisms of how to obtain the "weak" and "strong" force networks are not understood.

It was accidentally discovered that the specific granulometry as claimed in the present patent leads to the formation of networks of "strong" forces that consume an enormous amount of energy, making them the dominant dissipation mechanisms over the dissipation mechanisms mentioned in the state of the art: friction, viscoelastic damping, particle collision and viscothermal effect.

All acoustic insulation elements made of granular materials could form networks of common energy dissipation forces that lead to a certain sound pressure level reduction (SPLR), figure 2a.

An object of the invention is to use a specific granular granulometry and a specific size of the cavities to allow the formation of networks of strong forces that lead to a much greater reduction of the sound pressure level, figure 2b, than that known in the prior art. .

An acoustic insulation element is provided according to claim 1 that uses a strong force network as the main energy dissipation mechanism, wherein the strong force network is generated through complex interactions of solid particles in a granular system, which leads to the formation of a maximum number of interconnecting force pairs according to Newton's 3rd Law, wherein said strong force network is obtained using a granular material made of at least one solid material with biased multimodal granulometry specific. The acoustic insulation element comprises a granular material consisting of particles with a specific granulometry and a support structure having at least one cavity, wherein the at least one cavity is filled with particles of the granular material. The support structure simply serves to hold the granular material in a selected position in space, in particular in a vertical position.

The size of a particle can be defined as the diameter of a circle that surrounds the particle and touches its boundary at at least two points. Any other way of describing particle size, such as the diameter of an inner circle or the diameter of a spherical particle having an equivalent volume or mass, would equally well describe the claimed particle size distribution.

The acoustic insulation element according to claim 1 discloses a distribution that assigns a number of particles to an equivalent outside diameter of the particles that is selected such that the particles form a network of strong energy dissipating forces within the al least one cavity. Thus, the distribution that assigns a number of particles to an equivalent outside diameter of the particles is an asymmetric distribution, that is, it deviates from a symmetric distribution. Thus, the distribution of equivalent outer diameters of the particles is multimodal, having several modes. Thus, said multimodal distribution is skewed, such that said multimodal distribution has a maximum mode having a maximum number of particles assigned to a fundamental equivalent outer diameter of particles, and wherein said multimodal distribution has at least one previous mode and at least one later mode.

That is, said multimodal distribution is not symmetric to any of the modes.

The distribution of equivalent outer diameters of the particles is selected in such a way as to ensure a tight filling of the cavities with particles, which is required for the formation of a strong network of forces. In such a distribution, the diameters of the particles and their corresponding number of particles belonging to a given mode of the multimodal distribution must agree with a certain relationship, as described below.

It was found that such distribution multimodality should be skewed, for example negatively, as shown in Figure 4a, or positively, as shown in Figure 4c. Negatively biased multimodality has several correctly selected particle size modes, D¡-i, D¡- ² ,..., to the left of the maximal mode Di, while positively biased multimodality has several correctly selected particle size modes. , D¡+ ⁱ , D ^í+2 ,.., to the right of the maximum mode Di. In both cases, the multimodality bias is obtained by appropriate selection of the particle number Nk assigned to the corresponding equivalent outer diameter Dk of the modes, where k = ... i-3, i-2, i-1, i, i+1, i+2, i+3,....

It was found that the positive and negative bias of such multimodality lead to different types of strong force network topological shapes, which allow tuning of the frequency characteristics of the acoustic insulation.

For clarity, it should be noted that a departure from symmetry does not imply that a distribution is multimodal, and vice versa, multimodality does not imply that a distribution is skewed.

The invention is based on the intuitive understanding that sound insulation is essentially a process of dissipating the kinetic energy of vibrating air, respectively sound pressure waves that excite sound insulation, involving complex interactions between vibrating air and solid matter that reinforce the formation of a network of forces. Acoustic insulation according to the invention is not based on the properties of the material, as it is understood today and considered in the existing solutions available, but on a process of formation of networks of dissipative forces that are independent of the material. This is demonstrated in figures 3a to 3d, where the insulations were made from different granular materials, i.e. 3a - waste tires, 3b -LDPE, 3c - sawdust and 3d - PMMA, and all four insulations show the same frequency dependence of the insulation.

Therefore, the invention relates to acoustic insulation based on the formation of a strong network of forces between the granular particles within the support structure of the insulation element. The formation of the strong force network was found to be a very effective way of dispersing incoming sound pressure waves. The pressure wave is transmitted to the network of forces formed by the granular particles that are located in the cavities of the support structure. It was found that a correctly selected multimodal granulometry will lead to a very high force network energy absorption. At the same time, a properly selected granulometry will also minimize the remaining space between the particles that make up the network, which reinforces the transmission of sound pressure mainly through the network of forces, as shown, for example, in Fig. 4b and figure 4d.

It was also accidentally discovered that common particle distributions do not drive force networks with the efficiency that would prevail over the dissipation mechanisms mentioned in the state of the art. In the literature, such force networks are known as weak force networks. As an example, Figure 2 shows the comparison of the measured sound pressure level reduction of insulation made from sawdust with a common grading (see Figure 2a), resulting in a weak network of forces, and insulation made from sawdust. of the same sawdust after adjusting the distribution of sawdust particles according to the granulometry claimed in this case (see figure 2b), which results in a strong network of forces.

Surprisingly, it was found that the periodic generation of a network of forces requires continuous energy input and can be used as a dissipative mechanism. It was found that the amount of energy dissipated depends on the number of contact forces, which can be maximized by using granular materials with the claimed granulometry. Such a system of granular materials with a maximized number of contact forces represents a dissipative network of interacting bodies that is called a strong force network. It was also found that the periodic formation of a strong network of forces, reinforced by the periodic interaction of vibrating air, respectively sound, and granular materials with a defined granulometry, is the newly invented dissipative mechanism for regulating sound insulation.

In the case of sound pressure waves interacting with granular materials with a defined particle size distribution, these networks of strong forces periodically appear and disappear and dissipate an enormous amount of energy.

It was also discovered that by modifying the composition of the interacting particles by adjusting their sizes and numbers of particles with a given size, the size of a network of forces and the process of energy dissipation can be controlled. Properly selected distribution of particle diameters optimizes the size of the force network.

The acoustic insulation element according to the present invention comprises granular particles distributed in the cavities of the support structure, such as open cell foams, to allow the formation of networks of strong forces. Therefore, the invented acoustic insulation element does not depend on the material, but depends on the dissipative process.

Surprisingly, it was found that by proper selection of the granular particle sizes and their numerical ratio, size and structure, respectively, the topology of the strong force networks formed can be optimized in such a way that the force network dissipates an amount maximum energy. To increase the number of contact points of adjacent particles, and thus also reduce the separation between particles, it is beneficial to use particles with a very wide range of particle diameters.

Preferably, the particles of the granular material have an equivalent outer diameter that is between 0.0001 mm and 10 mm. Most preferably, the particles of the granular material have an equivalent outer diameter that is in a range between 0.001 mm and 4 mm. Especially particles having equivalent outer diameters in said range allow the formation of networks of strong forces.

Preferably, the at least one prior mode has a prior particle number assigned to a prior equivalent particle outside diameter that is less than the fundamental equivalent particle outside diameter of the maximum mode. In addition, the at least one posterior mode has a posterior particle number assigned to a posterior particle equivalent outside diameter that is greater than the fundamental equivalent particle outside diameter of the maximum mode.

The maximum number of particles is greater than the previous number of particles. The maximum number of particles is also greater than the number of subsequent particles.

According to a possible embodiment of the invention, the multimodal distribution has at least one section to the left of the maximum mode comprising several modes and comprising the maximum mode, where the number of particles assigned to the equivalent outside diameter of the particles decreases when the equivalent outer diameter of the particles decreases, such that an envelope curve over the mode peaks is negatively skewed. When the envelope curve over the mode peaks is negatively skewed, then the slope of the envelope curve is positive. Preferably, the negatively biased multimodality has at least two modes to the left of the maximum mode, as shown in Figure 4a.

In particular, the particles are chosen such that the multimodal distribution has at least one section comprising several modes and comprising the maximum mode, where a number of particles Nk assigned to the equivalent outside diameter Dk of any chosen mode k within said section is greater than a particle number assigned to the equivalent outer diameter of an adjacent mode, if the equivalent outer diameter Dk of the chosen mode k is greater than the equivalent outer diameter of the adjacent mode, such that an envelope curve over the modes is negatively biased within that section.

Preferably, within said section where the envelope curve over the mode peaks is negatively skewed, a ratio

RDk = ^{{D k /D k - i} k = i, i- i, i-2,... = { D i /D i- i , D i- i/D i-2 , D i-2 /D í- 3 ,... }}

is greater than or equal to 1.2 and is less than or equal to 2.1, such that 1.2 < RDk < 2.1, with k < i.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ^-1 assigned to the equivalent outside diameter Dk ^-1 of an adjacent mode k-1.

More preferably, within said section where the envelope curve over the mode peaks is negatively skewed, said RDk ratio is greater than or equal to 1.4 and is less than or equal to 1.9. Even more preferably, within said section where the envelope curve over the mode peaks is negatively skewed, said RDk ratio is greater than or equal to 1.5 and is less than or equal to 1.8.

Especially preferably, within said section where the envelope curve over the mode peaks is negatively skewed, a ratio

RDk = ^{{D k /D k - i}k = i, i- i, i-} 2 ^{, ... - { D / D i - i , D i - i / D i -} 2 ^, D ^/-2 / D ^/-3 ,...}

is equal to (1+V5)/2 or any integer multiplier of that value, such that RDk = (1 V5)/2 or RDk = n * (1 V5)/2, with k < i and n = integer.

Thus, a number of particles Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a number Nk ^-1 of particles assigned to the equivalent outside diameter Dk ^-1 of an adjacent mode k-1.

This ratio (1+V5) / 2, which is approximately 1.618, is also known as the golden ratio. Therefore, within such a negatively skewed section, the ratio RDk between an equivalent outside diameter Dk of a chosen mode k and an equivalent outside diameter Dk ^-1 of an adjacent mode k-1 preferably corresponds to the golden ratio or deviates of the golden ratio less than 30%, or less than 20%, or less than 10%.

According to another possible embodiment of the invention, the multimodal distribution has at least one section to the right of the maximum mode comprising several modes and comprising the maximum mode, where the number of particles assigned to the equivalent outside diameter of the particles decreases when the equivalent outer diameter of the particles increases, such that an envelope curve over the mode peaks is positively skewed. When the envelope curve over the mode peaks is positively skewed, then the slope of the envelope curve is negative. Preferably, the positively biased multimodality has at least two modes to the right of the maximum mode, as shown in Figure 4c.

In particular, the particles are chosen such that the multimodal distribution has at least one section comprising several modes and comprising the maximum mode, where a number of particles Nk assigned to the equivalent outside diameter Dk of any mode k chosen within said section is greater than a particle number assigned to the equivalent outer diameter of an adjacent mode, if the equivalent outer diameter Dk of the chosen mode k is less than the equivalent outer diameter of the adjacent mode, such that an envelope curve over the modes is positively biased within that section.

Preferably, within said section where the envelope curve over the mode peaks is positively skewed, a ratio

RDk = {Dk/Dk ⁺¹ }k=i, ^{i+ i, i+} 2 ^{, ... - { D / D i+ i , D i+ i /D i+} 2 ^{, D i+ 2 /D i+ 3 , ... }}

is greater than or equal to 0.45 and is less than or equal to 0.8, such that 0.45 < RDk < 0.8, with k > i.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ⁺¹ assigned to the equivalent outside diameter Dk ⁺¹ of an adjacent mode k+1.

More preferably, within said section where the envelope curve over the mode peaks is positively skewed, said RDk ratio is greater than or equal to 0.5 and is less than or equal to 0.75. Even more preferably, within said section where the envelope curve over the mode peaks is positively skewed, said RDk ratio is greater than or equal to 0.55 and is less than or equal to 0.7.

Especially preferably, within said section where the envelope curve over the mode peaks is positively skewed, a ratio

RDk - ^{{D k /D ki}k = i, i+1 i+2,... - { D i /D i+ i , D i+ i /D i+ 2 , D i+ 2 /D i+ 3 , ... }}

equals 2 / (1+V5) or any integer divisor of that value, such that RDk - 2/(1 V5) or RDk - 2/(n * (1 V5)), with k > i and n - integer.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk+i assigned to the equivalent outside diameter Dk+i of an adjacent mode k+1.

Said 2 / (1+V5) ratio, which is approximately 0.618, is the reciprocal value of the golden ratio. Therefore, within said section that is positively skewed, a ratio RDk between an equivalent outside diameter Dk of a chosen mode k, and an equivalent outside diameter Dk ⁺¹ of an adjacent mode k+1 preferably corresponds to the reciprocal of the golden ratio or deviates from the reciprocal value of the golden ratio by less than 30%, or less than 20%, or less than 10%.

According to a further advantageous development of the invention, within a section where the envelope curve over the mode peaks is negatively skewed, the ratios

RNk - ^{{N k /N k - i} k - i , i- i, i-2,... - { N / N i - i , N i- i /N i- 2 , ...} }

are greater than or equal to 1.2 and are less than or equal to 2.1, such that 1.2 < RNk < 2.1, with k < i.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ^-1 assigned to the equivalent outside diameter Dk ^-1 of an adjacent mode k-1.

Preferably, within said section where the envelope curve over mode peaks is negatively skewed, said RNk ratios are greater than or equal to 1.4 and are less than or equal to 1.9. More preferably, within said section where the envelope curve over the mode peaks is negatively skewed, said RNk ratios are greater than or equal to 1.5 and are less than or equal to 1.8.

According to a further advantageous development of the invention, within a section where the envelope curve over the mode peaks is negatively skewed, the ratios

RNk - ^{{ N k / N k - i } = iu -2 ,... - { N / N - i , N í- i / N í-2, ...} }

are equal to (1+V5)/ 2 or any integer multiplier of that value, such as RNk - (1 V5)/2 or RNk - n * (1 V5)/2, with k < i and n - integer.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ^-1 assigned to the equivalent outside diameter Dk ^-1 of an adjacent mode k-1.

This ratio (1+V5) / 2, which is approximately 1.618, is also known as the golden ratio. Therefore, within such a negatively skewed section, the RNk ratios between a number of particles Nk of a chosen mode k and a number of particles Nk ^-1 of an adjacent mode k-1 preferably correspond to the golden ratio or deviate of the golden ratio less than 30%, or less than 20%, or less than 10%.

Alternatively or additionally, within a section where the envelope curve over the mode peaks is positively skewed, the relationships

RNk - ^{{ N k /N ki} k - i , i+ i, i+ 2 ,... - { N / N ii , N i+ i /N i+ 2 , ... } N i+ i /N i+ 2 , . .} .} are greater than or equal to 1.2 and are less than or equal to 2.1, such that 1.2 < RNk < 2.1, with k > i.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ⁺¹ assigned to the equivalent outside diameter Dk ⁺¹ of an adjacent mode k+1.

Preferably, within said section where the envelope curve over mode peaks is positively skewed, said RNk ratios are greater than or equal to 1.4 and are less than or equal to 1.9. More preferably, within said section where the envelope curve over the mode peaks is positively skewed, said RNk ratios are greater than or equal to 1.5 and are less than or equal to 1.8.

Alternatively or additionally, within a section where the envelope curve over the mode peaks is positively skewed, the relationships

RNk - {Nk/Nk ⁺¹ }ki, i+ ¹ , ^í + ² ,... - {N /N i ⁺¹ , N ^/+1 /N ^/+2 ,...}

are equal to (1+V5)/ 2 or to any integer multiplier of said value, such that RNk - (1 V5)/2 or RNk - n * (1 V5)/2, with k > iyn = integer.

Thus, a particle number Nk assigned to the equivalent outside diameter Dk of a chosen mode k is greater than a particle number Nk ⁺¹ assigned to the equivalent outside diameter Dk ⁺¹ of an adjacent mode k+1.

This ratio (1+V5) / 2, which is approximately 1.618, is also known as the golden ratio. Therefore, within said section, which is positively skewed, the ratios RNk between a number of particles Nk of a chosen mode k and a number of particles Nk+i of an adjacent mode k+1 preferably correspond to the golden ratio or are deviate from the golden ratio less than 30%, or less than 20%, or less than 10%.

It was also discovered that said bias can be preferably obtained by mixing several groups of granular particles with different symmetric granulometry. Surprisingly, it was found that when several groups of granular particles with different average particle sizes are mixed, the number of particles is relevant to specify a number of individual group particles rather than their weight or volume.

It was found that such an arrangement according to the invention can establish an acoustic insulation element having noise absorption and reduction properties which are considerably better than those of elements known in the prior art. An acoustic insulation element according to the invention having the same thickness as a rigid foam board, for example, can have at least three times better noise reduction properties, measured in sound pressure level, than said foam board. rigid or soft foam board, or rock wool. The strong force network may, for example, be formed by particles made from ground waste tire rubber, or any other solid material or mixture thereof.

Noise reduction also depends on the acoustic frequency. The noise reduction ratio of the acoustic insulation element according to the invention compared to the noise reduction of a rigid foam panel having the same thickness varies with the variation of the acoustic frequency. As noted above, the frequency characteristics of the invented acoustic insulation can be tuned with multimodal granular grading bias tuning. However, within a given frequency range of, for example, 10 Hz to 20 kHz which is audible to the human being, the sound reduction of the sound insulation element according to the invention is nevertheless at least three times better, measured in sound pressure level, than the noise reduction of a rigid or soft foam board or rock wool of the same thickness.

Surprisingly, it was found that the energy dissipation process of strong force networks is material independent. Preferably, the particles of the granular material are solid. The particles can be produced from organic or non-organic solid material. The origin and chemical composition of the granular material are not important, as long as the rigidity of the particles is sufficient to form a network of strong dissipative forces. Therefore, the particles of a granular material can originate from various solid materials. For example, the particles can be made of metal, which has metallic bonds. The particles can also be made of a salt, which has ionic bonds. Furthermore, the particles can be made of a plastic material, which has covalent bonds. The particles can be made from an organic raw material as well as a non-organic raw material. In particular, the particles can be made of sand, polymer, rubber or wood. Consequently, the particles can be made from almost any organic or inorganic waste material, such as scrap tires, old bottles, wood dust, waist metals, stone dust, and the like. In fact, the granular particles can be produced by grinding any solid product that must not contain toxic substances.

All the particles, or almost all the particles, of the granular material can come from the same raw material. Therefore, the granular material contains only particles with one type of raw material and thus has a homogeneous composition of particles.

The particles of the granular material can also come from different raw materials. Therefore, the granular material contains a mixture of particles with various kinds of raw materials and thus has a heterogeneous composition of particles.

The granular material may contain particles with spherical geometry. Therefore, the particles are shaped like regular balls or pearls. In this case, the size of said particles can be expressed by their outer diameter. Granular material can also contain particles with complex geometry that deviate from regular ball or bead-like shapes. The size of said particles can be expressed by the equivalent outer diameter.

The equivalent outside diameter of such a particle corresponds to the outside diameter of a particle having spherical geometry and having the same volume or mass. Alternatively, the outer diameter of a particle can be defined as the diameter of a sphere in which the particle can be placed such that it touches the surface of a sphere at at least two points. The granular material may contain, in particular, a mixture of particles with a spherical geometry and particles with a complex geometry.

The particles of the granular material can have various types of structures. The granular material may contain particles that are solid, it can also contain particles that are hollow. The granular material may also contain particles that are porous. The granular material may contain, in particular, a mixture of particles with different structures and shapes.

The role of the support structure is simply to hold the granular material in place. Therefore, its role is only structural. Consequently, the support structure can be made of anything that fulfills this role. Preferably, the supporting structure is made of porous material, in particular, produced from organic or inorganic solid material, or woven from organic or inorganic fibers, or a structure produced by electrospinning or 3D printing.

The supporting structure can simply be any hollow space in the frame or body of the walls or floor of buildings or of the body structure of automobiles, train cars, boats, yachts, ships, aircraft, equipment housing that vibrate, and can simply be filled with granular material with a biased multimodal grading.

In another embodiment of the present invention, the support structure may have a porous composition and may have various types of structures and may be made of various types of materials. For example, the support structure may be made of a flexible material. The support structure can also be made of a rigid material. The support structure having a porous composition can be made of, for example, a single layer material. The support structure can also be made of a multilayer material.

The support structure may be made of porous foam. As another example, the support structure can be designed as a three-dimensional network. In particular, the support structure may be made of a woven fabric. Alternatively, the support structure may be made of a non-woven fabric.

The cavities of the support structure may have a complex geometry that deviates from a shape like a regular hollow sphere. The size of such cavities can be expressed by an equivalent inside diameter. The equivalent inside diameter of such a cavity corresponds to the inside diameter of a cavity having a hollow spherical geometry and having the same volume. Therefore, below, the size of the cavities in the support structure is expressed by their equivalent inside diameter.

The inside diameter of the cavities is greater than the equivalent outside diameter of the largest particles and, in addition, it must accommodate a sufficient number of smaller particles to fill the cavity and prevent movement of the particles in order to form the network of particles. strong forces. Preferably, the inner diameter is selected to be large enough to accommodate a sufficient number of particles of the entire particle size to maximize the number of contact points between the particles that form the network of strong forces.

Preferably, the particles are tightly arranged in the cavities such that the particles form a strong network of forces within the cavities. In particular, the particles of the granular material are arranged in the cavities of the support structure in such a way that the particles forming the strong force network within the cavities fill at least 70% of their volume.

According to a further development of the invention, when the support structure is made of a woven fabric or a non-woven fabric, said woven fabric or said non-woven fabric is preferably made of biofibres and/or synthetic fibers and/or a combination of these fibers. Again, in principle, it can be made of any material as long as it holds the granular particles in place in the required position.

According to another further development of the invention, when the support structure is made of a woven fabric or a non-woven fabric, said woven fabric or said non-woven fabric is made of metal fibers and/or glass fibers and/or of carbon fibers and/or of basalt fibers and/or of a combination of said fibers. Therefore, the support structure is resistant to high temperatures.

Preferably, in particular, if the support structure is resistant to high temperatures, the cavities of the support structure are filled with particles that are inorganic and also resistant to high temperatures. In particular, said particles are made of a material that resists high temperatures of up to 3400 C°.

According to an advantageous embodiment of the invention, the support structure is covered by a cover. The function of said cover is, in particular, to keep the granular particles inside the cavities of the support structure. It is an additional function of said cover to prevent dirt or moisture from entering the cavities of the support structure and coming into contact with the granular material. In one embodiment of the present invention, the cover may be non-porous.

In another embodiment of the present invention, the shell has pores with an equivalent pore diameter that is less than the equivalent outside diameter of the smallest particles. Such an arrangement allows sound waves to enter the insulation structure and the insulation adopts excellent sound absorption and insulation properties.

An acoustic insulation element according to the invention can be used in various applications. Such applications are especially automotive applications, mechanical engineering applications, electrical engineering applications, aerospace engineering applications, transportation engineering applications, marine engineering applications and civil engineering applications.

Subsequently, a method for producing granular material for an acoustic insulation element is described, wherein the particles of said granular material have a skewed multimodal distribution of their equivalent outer diameters with the appropriate ratio of their number and particle sizes in order to maximize the size of the strong dissipative force network. The method for producing said granular material includes the following steps:

In a first stage, granular material can be prepared from any solid substance regardless of its origin and chemical composition. The granular material can be prepared with any of the existing technologies currently used for grinding.

In a second stage, the granular raw material is filtered to separate the particles according to their equivalent outside diameters. Thus, particles with different average equivalent outside diameters are obtained with an approximately symmetric monomodal particle size distribution.

In a third step, those particles with different equivalent outer diameters corresponding to relevant modes are mixed according to the required ratios RDk and RNk of neighboring modes of the biased multimodal granulometry. Therefore, said mixture has a skewed multimodal distribution of outer diameters and can form the granular material to form networks of strong forces required within the acoustic insulation element.

Brief description of the drawings

Further details, embodiments and advantages of the present invention will become apparent from the following detailed description, given by way of example only, with reference to the drawings, in which:

Figure 1a is an exemplary illustration of a first sound transmission system according to the prior art,

Figure 1b is an exemplary illustration of a hypothetical second sound transmission system having ideal insulation properties,

Figure 1c is an exemplary illustration of a third prior art sound transmission system,

Figure 1d is an exemplary illustration of a fourth prior art sound transmission system,

Figure 2a is a graph that shows a reduction in the sound pressure level of an insulation made of sawdust with a common granulometry,

Figure 2b is a graph showing a reduction in the sound pressure level of an insulation made from the same sawdust with a granulometry according to the invention,

Figure 3a is a graph showing a reduction in the sound pressure level of an insulation made of rubber with a granulometry according to the invention,

Figure 3b is a graph showing a reduction in the sound pressure level of an insulation made of LDPE with a granulometry according to the invention,

Figure 3c is a graph showing a reduction in the sound pressure level of an insulation made of wood sawdust with a granulometry according to the invention,

Figure 3d is a graph showing a reduction in the sound pressure level of an insulation made of PMMA with a granulometry according to the invention,

Figure 4a is a schematic illustration of an equivalent outside diameter distribution with a negatively skewed multimodal section,

Figure 4b is a schematic illustration of a possible arrangement of particles having an outer diameter distribution according to Figure 4a with an enlarged area,

Figure 4c is a schematic illustration of an equivalent outside diameter distribution with a positively skewed multimodal section,

Figure 4d is a schematic illustration of a possible arrangement of particles having an outer diameter distribution according to Figure 4c with an enlarged area,

Figure 5 is a graph showing the frequency dependence of a sound pressure level reduction of insulation made from different common insulation materials compared to insulation made from a material with a particle size distribution according to the invention.

Figure 6 is a schematic illustration of a support structure in increased detail,

Figure 7 is a schematic sectional view of an acoustic insulation element in enlarged detail, Figures 8a and 8b are schematic illustrations of support structures made of woven fabric, respectively non-woven fabric,

Figure 9 is a car with increased details,

Figure 10 is a mobile home car with increased details,

Figure 11 is a boat with enlarged details,

Figure 12 is a train with increased details,

Figure 13 is an airplane with increased details,

Figure 14 is a residential house with increased details, and

Figure 15 is a schematic sectional view of an elevator in a building in enlarged detail.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The drawings provide only schematic views of the invention. Similar reference numerals refer to corresponding parts, elements or components throughout the figures, unless otherwise indicated. Detailed description

Fig. 1a is an exemplary illustration of a first sound transmission system 201 according to the prior art. The system 201 comprises a sound emitter 210 in the form of a loudspeaker, a sound receiver 212 indicated by a human ear, and a separating element 214 that separates the sound emitter 210 from the sound receiver 212. The numbers in the illustration are a example of how the emitted sound waves are reflected by the separating element 214, absorbed by the separating element 214 and transmitted by wave propagation.

In the present case, the partition element 214 is a rigid metal wall that cannot undergo any macroscopic vibration. In this case, approximately 88% of the emitted sound waves are reflected by the separating element 214 and only approximately 12% of the sound waves enter the separating element 214. Most of these sound waves are dissipated within the separating element. gap 214 and only about 1.4% of the sound waves are transmitted to the sound receiver 212. This means that a sound transmission loss is approximately:

STL = 20log(100/1.4) « 37dB

Figure 1b is an exemplary illustration of a hypothetical second sound transmission system 202 having ideal insulation properties. The system 202 comprises a sound emitter 210 in the form of a loudspeaker, a sound receiver 212 indicated by a human ear, and a separation element 214 separating the sound emitter 210 from the sound receiver 212.

In the present case, the partition element 214 is an absolutely rigid wall. That means the modulus of elasticity and stiffness of the spacer 214 are infinite. In this case, all emitted sound waves are reflected by the separation element 214.

Fig. 1c is an exemplary illustration of a third sound transmission system 203 according to the prior art. The system 203 comprises a sound emitter 210 in the form of a loudspeaker, a sound receiver 212 indicated by a human ear, and a separation element 214 separating the sound emitter 210 from the sound receiver 212. The numbers in the illustration are a example of how emitted sound waves are reflected by the separating element 214, are absorbed by separating element 214 and transmitted through separating element 214.

In the present case, the rigidity of the spacer 214 is relatively small. Thus, a substantial part of about 80% of the energy of the emitted sound waves is transmitted by means of macroscopic vibrations of the separating element 214 and only about 20% of the emitted sound waves are reflected by the separating element 214.

Figure 1d is an exemplary illustration of a fourth sound transmission system 204 according to the prior art. System 204 comprises a sound emitter 210 in the form of a loudspeaker, a sound receiver 212 indicated by a human ear, and a separation element 214 that separates the sound emitter 210 from the sound receiver 212. The numbers in the illustration are a example of how emitted sound waves are reflected by separating element 214, absorbed by separating element 214, and transmitted through separating element 214.

In the present case, the separating element 214 is an elastic wall with an insulating material fixed on it, guaranteeing direct contact between the elastic and the insulating material. In this case, the pressure waves are transmitted directly from the elastic wall to the insulating material through the contact between two solid bodies. Furthermore, the vibrating elastic wall will also impose the macroscopic vibrations of the insulating material. In this case, the separation element 214 acts essentially more as a vibration isolation than as an acoustic isolation. Thus, approximately 70% of the energy of the emitted sound waves is transmitted through the separating element 214, 10% is dissipated within the separating element 214, and only approximately 20% of the emitted sound waves are reflected in the spacer. separating element 214.

Figure 2 is an exemplary comparison of the measured SPLR sound pressure level reduction of insulation made from sawdust. Thus, Figure 2a is a graph showing the reduction of the sound pressure level SPLR against a frequency F of an insulation made of sawdust with a common granulometry. Figure 2b is a graph showing a reduction in the sound pressure level SPLR against a frequency F of an insulation made of the same sawdust with a granulometry that is adjusted according to the invention.

Figure 3 is an exemplary demonstration that the performance of the new strong force network acoustic insulation is material independent. Figure 3 presents a comparison of four isolates made from different pellet materials. Figure 3a is a graph showing a sound pressure level reduction SPLR versus frequency F of insulation made from waste tire rubber with a gradation adjusted in accordance with the invention. Figure 3b is a graph showing a reduction in the sound pressure level SPLR against a frequency F of an insulation made of LDPE (low density polyethylene) with a granulometry that is adjusted according to the invention. Figure 3c is a graph showing a reduction in the sound pressure level SPLR versus a frequency F of an insulation made of wood sawdust with a granulometry that is adjusted according to the invention. Figure 3d is a graph showing a reduction in the sound pressure level SPLR against a frequency F of an insulation made of PMMA (polymethyl methacrylate) with a granulometry that is adjusted according to the invention. All four isolates show nearly identical performance.

Figure 4a is a schematic illustration of an equivalent outside diameter distribution with a negatively skewed multimodal section. The negatively skewed section of the multimodal distribution has a maximum mode i having a maximum number Ni of 14 particles assigned to a fundamental equivalent outside diameter Di of 14 particles.

The negatively skewed multimodal section of the multimodal distribution has a prior mode i-1 having a prior number N ^¡-1 of particles assigned to an equivalent prior outer diameter Di ^-1 of particles 14 and another mode having a prior number Ni ^-2 of particles 14 assigned to an equivalent outside diameter Di ^-2 of particles 14 and another way that has a Ni ^-3 number of particles 14 assigned to an equivalent outside diameter Di ^-3 of particles 14. Thus, the number of particles Nk assigned to the Equivalent outside diameter Dk of the modes increases with increasing equivalent outside diameter Dk:

Dk > Dk ^-1 and Nk > Nk ^-1 for k < i

Currently, within such a negatively biased multimodality section, a ratio RDk between an equivalent outside diameter Dk of a chosen mode k, and an equivalent outside diameter Dk ^-1 of an adjacent mode k-1 is equal to (1+V5 ) / 2 or to any integer multiple of that value:

RDk = Dk/Dk ^-1 = n *(1+V5)/2

with n = integer

Currently, within said negatively biased multimodality section, a ratio RNk between a number Nk of a chosen mode k, and a number Nk ^-1 of an adjacent mode k-1 is equal to (1+V5)/ 2 or a any integer multiple of that value.

RNk = Nk/Nk-i = n *(1+V5)/2

with n = integer

The multimodal distribution further has a posterior mode i+1 that has a posterior number Ni ⁺¹ of 14 particles assigned to a posterior equivalent outside diameter Di ⁺¹ of particles 14. However, said posterior mode i+1 is not part of the multimodal distribution. negatively skewed multimodality section of the multimodal distribution.

Figure 4b is a schematic illustration of a possible arrangement of particles 14 having an outside diameter distribution according to Figure 4a with an enlarged area. For ease of presentation, the particles 14 are shown as regular balls with spherical geometry.

Currently, three particles 14 having the maximum diameter Di of the maximum mode are arranged in such a way that they touch each other and leave an intermediate space between them. Two particles 14 having the anterior diameter Di- ¹ of the anterior mode i-1 are disposed within said intermediate space, as well as one particle having the diameter Di- ² of the adjacent mode.

Figure 4c is a schematic illustration of an equivalent outside diameter distribution with a positively skewed multimodal section. The positively skewed section of the multimodal distribution has a maximum mode i that has a maximum number Ni of 14 particles assigned to a fundamental equivalent outer diameter Di of 14 particles.

The positively skewed multimodal section of the multimodal distribution has one posterior mode i+1 having a posterior number Ni ⁺¹ of particles 14 assigned to an equivalent posterior outer diameter Di ⁺¹ of particles 14 and another mode having a posterior number Ni ⁺² number 14 assigned to an equivalent outside diameter Di ⁺² of particles 14 and another mode having a Ni ⁺³ number of particles 14 assigned to an equivalent outside diameter Di ⁺³ of particles 14. Thus, the number of particles Nk assigned to the Equivalent outer diameter Dk of the modes decreases with increasing equivalent outer diameter Dk:

Dk < Dk+1 and Nk > Nk ⁺¹ for k > i

Currently, within such a positively skewed multimodality section, a ratio RDk between an equivalent outside diameter Dk of a chosen mode k, and an equivalent outside diameter Dk ⁺¹ of an adjacent mode k+1 is equal to (1+V5 ) / 2 or to any integer divisor of that value:

RDk = Dk/Dk ⁺¹ = 2/(n*(1-V5))

with n = integer

Currently, within such a positively biased multimodality section, a ratio RNk between a number Nk of a chosen mode k, and a number Nk ⁺¹ of an adjacent mode k+1 is equal to (1+V5)/ 2 or a any integer multiple of that value.

RNk = Nk/Nk ⁺¹ = n *(1+V5)/2

with n = integer

The multimodal distribution also has a prior mode i-1 that has a prior number N ^m of particles 14 assigned to an equivalent prior outer diameter Di ^-1 of particles 14. However, said prior mode i-1 is not part of the section of positively skewed multimodality of the multimodal distribution.

Figure 4d is a schematic illustration of a possible arrangement of particles 14 having an outside diameter distribution according to Figure 4c with an enlarged area. For ease of presentation, the particles 14 are shown as regular balls with spherical geometry.

Currently, four particles 14 having the diameter Di ⁺² of the mode adjacent to the rear mode i + 1 adjacent to the maximum mode i are arranged in such a way that they touch each other and leave an intermediate space between them. Several particles 14 having the posterior diameter Di ⁺¹ of the posterior mode i+1 adjacent to the maximum mode i are arranged within said intermediate space as well as several particles having the fundamental diameter Di of the maximum mode i.

Figure 5 is a graph showing a sound pressure level reduction SPLR versus frequency F of insulation made of different materials with a common grain size compared to insulation made of a material 305 with a grain size according to the invention. Thus, graphs are provided for Styropor 301, Stonewool 302, Styrodur 303 and a high-end commercial sound insulation material called "FAI30M" 304.

Figure 5 is an exemplary comparison of measurements of the new insulation that forms a strong network of forces compared to typical commercial insulations. In the present case, the new isolation based on a strong network of forces outperforms the existing isolation by several orders of magnitude. In particular, the improvement of sound insulation at lower frequencies in reducing the pressure of sound waves is at least three times, while at higher frequencies, above 3000 Hz, the improvement is more than ten times. The sound wave pressure p is calculated as

p = ^p0 * 10(SPLR/20) [Pa]

Thus, p ⁰ is a reference sound wave pressure and SPLR is the measured sound pressure level reduction.

Figure 6 is a schematic illustration of a possible support structure 40 in enlarged detail. The support structure 40 comprises walls 41 surrounding the cavities 42. In the illustration given, the walls 41 are almost straight and have slight curves, while the walls 41 are regularly arranged. In particular, in the given presentation, the walls 41 are arranged parallel, respectively orthogonal to each other, and the cavities 42 have an almost rectangular shape and each cavity 42 is surrounded by at least four walls 41. The cavities 42 may be additionally surrounded by a top wall and a bottom wall not shown in this illustration.

However, the walls 41 of the support structure can also be arranged irregularly and asymmetrically. Therefore, the cavities 42 of the support structure 40 can also have an irregular shape. Furthermore, the cavities 42 may have, for example, a spherical shape.

Figure 7 is a schematic sectional view of an acoustic insulation element 10 in enlarged detail. The acoustic insulation element 10 comprises the support structure 40 shown in Figure 6, wherein the cavities 42 of said support structure 40 are filled with a granular material 12. The granular material 12 of the acoustic insulation element 10 contains particles granular particles 14. As can be seen, in particular, in the enlarged detail, the particles 14 have a different size and therefore have different equivalent outer diameters D. The equivalent outer diameters D and the respective numbers N of the granular particles 14 they need to be in the proper ratio to ensure a desired size of a strong dissipative force network. For the sake of visibility, the cavities shown are not completely filled with particles.

In principle, the support structure 40 can take any structural form as long as it maintains the granular particles 14 of the granular material 12 in a desired position in space and allows complex interactions of the granular particles 14 from a strong network of forces.

The support structure 40 is covered by a cover 50 which is only partially visible in the given presentation. Cover 50 prevents granular particles 14 of granular material 12 from falling out of cavities 42 of support structure 40. Cover 50 also prevents dirt or moisture from entering cavities 42 of support structure 40 and, therefore come into contact with the particles 14 of the granular material 12.

In the present case, the cover 50 is non-porous. In other embodiments of the invention, the cover 50 may be made of a porous material having pores with an equivalent pore diameter that is less than the equivalent outside diameter D of the smallest granular particles 14. In such an arrangement, sound waves will penetrate in the insulation structure and will substantially reduce the reflection of sound waves. Such insulation will show excellent sound absorption and sound insulation characteristics.

Figure 8a is a schematic illustration of a support structure 40 made of woven fabric 45. The support structure 40 is designed as a three-dimensional network having a nearly regular shape. Included within the support structure 40 and surrounded by the woven fabric 45 are a plurality of cavities 42 for receiving the granular particles 14.

Figure 8b is a schematic illustration of a support structure 40 made of nonwoven fabric 46. The support structure 40 is designed as a three-dimensional net having an irregular shape. Included within the support structure 40 and surrounded by the nonwoven fabric 46 are a plurality of cavities 42 for receiving the granular particles 14.

Figure 9 shows a passenger car 60 with enlarged detail sectional views of various parts that can be equipped with acoustic insulation elements 10. Said parts comprise, among others, an engine hood 61, a roof structure 62, a casement 63, a pillar 64 or a door 65.

A sound insulation element 10 used in the engine hood 61 to reduce the noise of a combustion engine is preferably created to be resistant to temperature. Alternatively, or additionally, the acoustic insulation element 10 can be placed directly on the combustion engine.

Structural elements of the car 60 that are hollow, for example, the wings 63, the pillars 64 or the door parts 65, can alternatively be filled with particles 14 of the granular material 12 directly without providing an explicit support structure 40 having a porous composition.

Figure 10 shows a mobile home car 70 with enlarged detail sectional views of various parts that can be equipped with sound insulation elements 10. Said parts include, among others, an engine hood 71, a pillar 74 or walls. sides 72 surrounding a habitable cabin.

A sound insulation element 10 used in the engine hood 61 to reduce the noise of a combustion engine is preferably created to be resistant to temperature. Alternatively, or additionally, the acoustic insulation element 10 can be placed directly on the combustion engine.

Structural elements of the mobile home car 70 that are hollow, for example, the pillars 64 or the side walls 72, may alternatively be filled with the particles 14 of the granular material 12 directly without providing an explicit support structure 40 having a porous composition.

Figure 11 shows a boat 80 with enlarged detail sectional views of various parts that can be equipped with the acoustic insulation elements 10. Said parts comprise, among others, an outer wall 81, inner walls 82 surrounding a habitable cabin or partition walls 83 dividing a combustion engine or gearbox compartment from the habitable cabin.

An acoustic insulation element 10 used in the partition walls 83 is preferably created resistant to temperature. Alternatively, or additionally, the acoustic insulation element 10 can be placed directly in the combustion engine compartment or in the gearbox.

Structural elements of the vessel 80 that are hollow, for example, segments of the outer wall 81 or inner walls 82, may alternatively be filled with the particles 14 of the granular material 12 directly without providing explicit support structure 40 . having a porous composition. It is also possible to fill a hollow space of a structural element, for example of a partition wall 83, with the particles 14 of the granular material 12 directly and to place an additional acoustic insulation element 10 on said structural element.

Figure 12 shows a train 90 with enlarged detail sectional views of various parts that can be equipped with acoustic insulation elements 10. Said parts comprise, among others, outer walls 91, inner walls 92 or ceiling structures 95.

Structural elements of train 90 that are hollow may alternatively be filled with particles 14 of granular material 12 directly without providing an explicit support structure 40 having a porous composition. It is also possible to fill a hollow space of a structural element, for example, of an outer wall 91, with the particles 14 of the granular material 12 directly and to place an acoustic insulation element 10 additionally on said structural element.

Figure 13 shows an aircraft 100 with enlarged detail sectional views of various parts that can be equipped with the acoustic insulation elements 10. Said parts comprise, among others, exterior walls 101, interior walls 102 that divide compartments of the aircraft 100 or a 105 turbine engine.

An acoustic insulation member 10 used in the turbine engine 105 is preferably made high-temperature resistant, withstanding high temperatures up to 2000°C.

Preferably, the acoustic insulation element 10 is placed directly on the turbine engine 105. Thus, the acoustic insulation element 10 surrounds the turbine engine 105 as a cylindrical housing that adapts to the geometry of the turbine engine 105, where a leading end and a trailing end remain open.

Figure 14 shows a residential house 110 with enlarged detail sectional views of various parts that can be equipped with sound insulation elements 10. Said parts include, among others, window frames 112 or doors 114. Other parts not shown are , for example, bathroom walls, sanitary pipes and heating installations. Elements of the residential house 110 that are hollow may alternatively be filled with the particles 14 of the granular material 12 directly without providing an explicit support structure 40 having a porous composition.

Figure 15 shows a sectional view of an elevator 120 in a building 122 with a sectional view of an enlarged detail of a car wall 124 that can be equipped with an acoustic insulation element 10. In addition, the side walls of a shaft for the elevator in the building 122 can be equipped with an acoustic insulation element 10. The car walls 124 which are hollow can alternatively be filled with the particles 14 of the granular material 12 directly without providing an explicit support structure 40 having a composition porous

Although the present invention has been described herein in detail in connection with one or more preferred embodiments, it is to be understood that the present disclosure is illustrative and exemplary of the present invention only and is made merely for the purpose of providing an exemplary disclosure. complete and enabling of the invention. The foregoing disclosure is not intended to be construed as a limitation on the present invention or to otherwise exclude any other embodiment, adaptation, variation, modification, or equivalent arrangement; the present invention being defined by the claims appended hereto.

Reference symbols

10 Sound insulation element

12 granular material

14 particles

40 Support Structure

41 wall

42 Cavity

45 Woven Fabric

46 Non-woven fabric

50 deck

60 tourism

61 engine hood

62 Roof structure

63 Swing

64 Pillar

65 door

70 mobile home car

71 engine hood

72 Sidewall

74 Pillar

80 ship

81 outer wall

82 inner wall

83 partition wall

90 train

91 outer wall

92 inner wall

95 roof structure

100 plane

101 outer wall

102 inner wall

105 turbine engine

110 residential house

112 window frame

114 door

120 elevator

122 building

124 cabin wall

201 First sound transmission system

202 Second sound transmission system

203 Third sound transmission system

204 Fourth sound transmission system

210 sound emitter

212 sound receiver

214 Separation element

301 Styrofoam

302 Stonewool

303 Styrodur

304 FAI30M

305 material with particle size distribution according to the invention

i Maximum mode serial number

i-1 Serial number of the previous mode

i+1 Rear mode serial number

D Equivalent outside diameter

Di Fundamental equivalent outer diameter of maximum mode

Di-i Previous equivalent outside diameter of the previous mode

Di+i Rear Equivalent Outside Diameter of Rear Mode

N Number of particles

Ni Maximum number of particles of the maximum mode

Ni ^-1 Previous number of particles of the previous mode

Ni ⁺¹ Posterior number of particles of the posterior mode

p sound wave pressure

p ⁰ Reference sound wave pressure

SPLR Sound Pressure Level Reduction

STL Sound Transmission Loss

Claims (17)

1. Acoustic insulation element (10), which uses a strong network of forces as the main energy dissipation mechanism, where the strong force network is generated through complex interactions of solid particles (14) in a granular system, leading to the formation of a maximum number of interconnecting force pairs according to Newton's 3rd Law, where said strong force network is obtained using a granular material (12) made of at least one solid material with a specific biased multimodal granulometry, that understands a granular material (12) consisting of particles (14), and a support structure (40) having at least one cavity (42), wherein the at least one cavity (42) is filled with the particles (14) of the granular material (12), where a distribution is selected that assigns a number (N) of particles (14) to an equivalent outside diameter (D) of the particles (14), in such a way that the particles (14) form a network of strong dissipation forces of energy within the at least one cavity (42), where the distribution that assigns a number (N) of particles (14) to an equivalent outer diameter (D) of the particles (14) is an asymmetric distribution, where the distribution of the equivalent outside diameters (D) of the particles (14) is multimodal, having several modes, and where said multimodal distribution is skewed, in such a way that said multimodal distribution has a maximum mode (i) having a maximum number (Ni) of particles (14) assigned to a fundamental equivalent outside diameter (Di) of particles (14), and where said multimodal distribution has at least one prior mode (i-1) and at least one subsequent mode (i+1). 2. Acoustic insulation element (10) according to claim 1, wherein the particles (14) have an equivalent outer diameter (D) that is between 0.0001 mm and 10 mm. Sound insulation element (10) according to one of the preceding claims, wherein the at least one prior mode (i-1) has a prior number (N ^m ) of particles (14) assigned to a prior equivalent outside diameter (Dm ) of particles (14) that is less than the fundamental equivalent outside diameter (Di) of particles (14), and wherein the at least one back mode (i+1) has a back number (Ni ⁺¹ ) of particles (14) assigned to a back equivalent outside diameter (Di ⁺¹ ) of particles (14) which is larger than the fundamental equivalent outside diameter (Di) of particles (14). Sound insulation element (10) according to one of the preceding claims, where the multimodal distribution has at least one section to the left of the maximum mode (i) comprising several modes and comprising the maximum mode (i), wherein the number (N) of particles (14) assigned to the equivalent outside diameter (D) of the particles (14) decreases when the equivalent outside diameter (D) of the particles (14) decreases, such that an envelope curve over the mode peaks is negatively skewed. 5. Acoustic insulation element (10) according to claim 4, wherein within that section where the envelope curve over the mode peaks is negatively skewed, a relation RDk = ^{{ D k} / ^{D k -i}k = i, i-} 1 ^, i ^-2 ,... = ^{{ D i / D í a , D í a ID í} -2 ^, D ^/.2 ID ^/-3 ,...} is greater than or equal to 1.2 and is less than or equal to 2.1, such that 1.2 < RDk < 2.1, where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk ^-1 ) assigned to the equivalent outside diameter (Dk ^-1 ) of an adjacent mode (k-1). 6. Acoustic insulation element (10) according to one of claims 4 to 5 where within said section in which the envelope curve over the mode peaks is negatively skewed, a relation RDk = ^{{D k /D k - i} k = i i- i ,} iz,... = ^{{ D / D i} -1 ^{, D í- i / D í} -2 , ^{D í-2 /D í-3,} ...} is equal to (1+V5)/ 2 or any integer multiplier of that value, such that RDk = (1 V5)/2 or RDk = ⁿ * (1 V5)/2 where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk-i) assigned to the equivalent outside diameter (Dk- ¹ ) of an adjacent mode (k-1). Sound insulation element (10) according to one of the preceding claims, where the multimodal distribution has at least one section to the right of the maximum mode (i) comprising several modes and comprising the maximum mode (i), wherein the number (N) of particles (14) assigned to the equivalent outside diameter (D) of the particles (14) decreases as the equivalent outside diameter (D) of the particles (14) increases, such that an envelope curve over the mode peaks is positively skewed. 8. Acoustic insulation element (10) according to claim 7, wherein within that section where the envelope curve over the mode peaks is positively skewed, a relation RDk = ^{{ D k / D kn }k = i, i+} 1 ^, + ² ,... = ^{{ D / D i+ i , D ii / D i} 2 ^{, D i+} 2 ^{/ D} 3 ^{, ... }} is greater than or equal to 0.45 and is less than or equal to 0.8, such that 0.45 < RDk < 0.8, where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk+ ¹ ) assigned to the equivalent outside diameter (Dk+ ¹ ) of an adjacent mode (k+1). Sound insulation element (10) according to one of claims 7 to 8 where within said section in which the envelope curve over the mode peaks is positively skewed, a relation RDk = ^{{D k /D ki}k = i, i+ i,} 2 ^{, ... = { D / D i , D i + i / D} 2 ^{, D i+ 2 /D i+ 3 , ... }} is equal to 2 / (1+V5) or to any integer divisor of that value, such that RDk = 2/(1 V5) or RDk = 2/(n * (1 V5)) where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk+ ¹ ) assigned to the equivalent outside diameter (Dk+ ¹ ) of an adjacent mode (k+1). 10. Acoustic insulation element (10) according to claim 4, wherein within a section where the envelope curve over the mode peaks is negatively skewed, the relations RNk = ^{N k /N k - i}k = i,} - ¹ , i- ² ,... = ^{{ N 1 N i- i , N i - n N -} 2 ^{, .. . }} are greater than or equal to 1.2 and less than or equal to 2.1, such that 1.2 < RNk < 2.1, where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is larger than a number (Nk- ¹ ) assigned to the equivalent outside diameter (Dk- ¹ ) of an adjacent mode (k-1). 11. Acoustic insulation element (10) according to claim 4, wherein within a section where the envelope curve over the mode peaks is negatively skewed, the relations RNk = ^{{ N k /N k - i} k = i ,} i- ¹ , i ^-2 ,... = ^{{ N / N i- i , N - i / N} i- ² ,...} are equal to (1+V5)/ 2 or to any integer multiplier of that value, such that RNk = (1 V5)/2 or RNk = ⁿ * (1 V5)/2 where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk-i) assigned to the equivalent outside diameter (Dk- ¹ ) of an adjacent mode (k-1). 12. Acoustic insulation element (10) according to claim 7, wherein within a section where the envelope curve over the mode peaks is positively skewed, the relations RNk = ^{{N k /N ki} k = ii+} 1 ^, i+ ² ,... = ^{{ N i / N i ,} N ,+ ¹ /M+ ² ,... } are greater than or equal to 1.2 and less than or equal to 2.1, such that 1.2 < RNk < 2.1, where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk+ ¹ ) assigned to the equivalent outside diameter (Dk+ ¹ ) of an adjacent mode (k+1). 13. Acoustic insulation element (10) according to claim 7, wherein within a section where the envelope curve over the mode peaks is positively skewed, the relations RNk = ^{{N k /N ki} k = i, i+ i, i+} 2 ^{, ... = { N / N i , N i + i / N} 2 ^{, .. . }} are equal to (1+V5)/ 2 or any integer multiplier of that value, such that RNk = (1 V5)/2 or RNk = ⁿ * (1 V5)/2 where a number (Nk) assigned to the equivalent outside diameter (Dk) of a chosen mode (k) is greater than a number (Nk+i) assigned to the equivalent outside diameter (Dk+i) of an adjacent mode (k+1). Acoustic insulation element (10) according to one of the preceding claims, wherein the at least one cavity (42) has an equivalent inner diameter that is selected large enough so that a sufficient number of particles (14) can form the strong network of forces. Sound insulation element (10) according to one of the preceding claims, wherein the particles (14) are closely arranged in the at least one cavity (42) in such a way that the particles (14) form a network of strong forces within the at least one cavity (42). Acoustic insulation element (10) according to one of the preceding claims, in which the support structure (40) is covered by a cover (50). 17. Use of an acoustic insulation element (10) according to any of the preceding claims in automotive applications, in mechanical engineering applications, in electrical engineering applications, in aerospace engineering applications, in transport applications, in applications marine engineering or civil engineering applications.